diff --git a/applications/solvers/multiphase/icoReactingMultiphaseInterFoam/laserDTRM/laserDTRM.C b/applications/solvers/multiphase/icoReactingMultiphaseInterFoam/laserDTRM/laserDTRM.C
index 41b5a02546..6296b29bf9 100644
--- a/applications/solvers/multiphase/icoReactingMultiphaseInterFoam/laserDTRM/laserDTRM.C
+++ b/applications/solvers/multiphase/icoReactingMultiphaseInterFoam/laserDTRM/laserDTRM.C
@@ -707,7 +707,7 @@ void Foam::radiation::laserDTRM::calculate()
         Pstream::gatherList(p0);
         Pstream::scatterList(p0);
 
-        for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             const pointField& pos = positions[proci];
             const pointField& pfinal = p0[proci];
diff --git a/applications/test/parallel-nonBlocking/Test-parallel-nonBlocking.C b/applications/test/parallel-nonBlocking/Test-parallel-nonBlocking.C
index 1d9eeebcca..7fca05e3c2 100644
--- a/applications/test/parallel-nonBlocking/Test-parallel-nonBlocking.C
+++ b/applications/test/parallel-nonBlocking/Test-parallel-nonBlocking.C
@@ -50,7 +50,6 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
-
     #include "setRootCase.H"
     #include "createTime.H"
 
@@ -154,7 +153,7 @@ int main(int argc, char *argv[])
     {
         PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
-        for (label proci = 0; proci < Pstream::nProcs(); proci++)
+        for (const int proci : Pstream::allProcs())
         {
             UOPstream toProc(proci, pBufs);
             toProc << Pstream::myProcNo();
@@ -164,7 +163,7 @@ int main(int argc, char *argv[])
         pBufs.finishedSends();
 
         // Consume
-        for (label proci = 0; proci < Pstream::nProcs(); proci++)
+        for (const int proci : Pstream::allProcs())
         {
             UIPstream fromProc(proci, pBufs);
             label data;
diff --git a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/DelaunayMesh/DistributedDelaunayMesh.C b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/DelaunayMesh/DistributedDelaunayMesh.C
index e02810916d..56b18a898a 100644
--- a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/DelaunayMesh/DistributedDelaunayMesh.C
+++ b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/DelaunayMesh/DistributedDelaunayMesh.C
@@ -489,7 +489,7 @@ Foam::label Foam::DistributedDelaunayMesh<Triangulation>::referVertices
 
     pointMap.distribute(parallelVertices);
 
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         const labelList& constructMap = pointMap.constructMap()[proci];
 
diff --git a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/backgroundMeshDecomposition/backgroundMeshDecomposition.C b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/backgroundMeshDecomposition/backgroundMeshDecomposition.C
index 1b022e59e4..4b50b014ca 100644
--- a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/backgroundMeshDecomposition/backgroundMeshDecomposition.C
+++ b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/backgroundMeshDecomposition/backgroundMeshDecomposition.C
@@ -473,7 +473,7 @@ void Foam::backgroundMeshDecomposition::printMeshData
 
     // globalIndex globalBoundaryFaces(mesh.nBoundaryFaces());
 
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         Info<< "Processor " << proci << " "
             << "Number of cells = " << globalCells.localSize(proci)
diff --git a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshConformToSurface.C b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshConformToSurface.C
index 2ba63abf1a..4affaa5758 100644
--- a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshConformToSurface.C
+++ b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshConformToSurface.C
@@ -703,7 +703,7 @@ Foam::label Foam::conformalVoronoiMesh::synchroniseSurfaceTrees
     label nStoppedInsertion = 0;
 
     // Do the nearness tests here
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         // Skip own points
         if (proci >= Pstream::myProcNo())
@@ -795,7 +795,7 @@ Foam::label Foam::conformalVoronoiMesh::synchroniseEdgeTrees
     label nStoppedInsertion = 0;
 
     // Do the nearness tests here
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         // Skip own points
         if (proci >= Pstream::myProcNo())
diff --git a/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C b/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
index 51a68564c5..111ef191cc 100644
--- a/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
+++ b/applications/utilities/mesh/generation/foamyMesh/foamyHexMeshBackgroundMesh/foamyHexMeshBackgroundMesh.C
@@ -130,7 +130,7 @@ void printMeshData(const polyMesh& mesh)
     label totProcPatches = 0;
     label maxProcFaces = 0;
 
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         Info<< endl
             << "Processor " << proci << nl
diff --git a/applications/utilities/parallelProcessing/redistributePar/redistributePar.C b/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
index 96f7bc50df..fd916b8476 100644
--- a/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
+++ b/applications/utilities/parallelProcessing/redistributePar/redistributePar.C
@@ -185,7 +185,7 @@ void printMeshData(const polyMesh& mesh)
     label totProcPatches = 0;
     label maxProcFaces = 0;
 
-    for (label procI = 0; procI < Pstream::nProcs(); ++procI)
+    for (const int procI : Pstream::allProcs())
     {
         Info<< nl
             << "Processor " << procI << nl
diff --git a/applications/utilities/preProcessing/viewFactorsGen/shootRays.H b/applications/utilities/preProcessing/viewFactorsGen/shootRays.H
index 9a44e73add..9f751ecd20 100644
--- a/applications/utilities/preProcessing/viewFactorsGen/shootRays.H
+++ b/applications/utilities/preProcessing/viewFactorsGen/shootRays.H
@@ -7,7 +7,7 @@ const label maxDynListLength
     viewFactorDict.getOrDefault<label>("maxDynListLength", 100000)
 );
 
-for (label proci = 0; proci < Pstream::nProcs(); proci++)
+for (const int proci : Pstream::allProcs())
 {
     // Shoot rays from me to proci. Note that even if processor has
     // 0 faces we still need to call findLine to keep calls synced.
diff --git a/src/OpenFOAM/containers/Lists/SortableList/ParSortableList.C b/src/OpenFOAM/containers/Lists/SortableList/ParSortableList.C
index d4099adc6b..5e66e78be7 100644
--- a/src/OpenFOAM/containers/Lists/SortableList/ParSortableList.C
+++ b/src/OpenFOAM/containers/Lists/SortableList/ParSortableList.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -285,7 +286,7 @@ void Foam::ParSortableList<Type>::sort()
 
     label combinedI = 0;
 
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         if (proci == Pstream::myProcNo())
         {
diff --git a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamBuffers.H b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamBuffers.H
index 1904922c78..df57475824 100644
--- a/src/OpenFOAM/db/IOstreams/Pstreams/PstreamBuffers.H
+++ b/src/OpenFOAM/db/IOstreams/Pstreams/PstreamBuffers.H
@@ -39,7 +39,7 @@ Description
     \code
         PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
-        for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             if (proci != Pstream::myProcNo())
             {
@@ -52,7 +52,7 @@ Description
 
         pBufs.finishedSends();   // no-op for blocking
 
-        for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             if (proci != Pstream::myProcNo())
             {
@@ -62,7 +62,6 @@ Description
         }
     \endcode
 
-
 SourceFiles
     PstreamBuffers.C
 
diff --git a/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H b/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
index f963347395..4628871b30 100644
--- a/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
+++ b/src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H
@@ -75,7 +75,7 @@ public:
     static const Enum<commsTypes> commsTypeNames;
 
 
-    // Public classes
+    // Public Classes
 
         //- Structure for communicating between processors
         class commsStruct
@@ -180,7 +180,7 @@ public:
 
 private:
 
-    // Private data
+    // Private Data
 
         //- By default this is not a parallel run
         static bool parRun_;
@@ -248,7 +248,7 @@ private:
 
 protected:
 
-    // Protected data
+    // Protected Data
 
         //- Communications type of this stream
         commsTypes commsType_;
@@ -298,7 +298,7 @@ public:
         {}
 
 
-    // Member functions
+    // Member Functions
 
         //- Allocate a new communicator
         static label allocateCommunicator
@@ -424,7 +424,7 @@ public:
             return haveThreads_;
         }
 
-        //- Number of processes in parallel run
+        //- Number of processes in parallel run, and 1 for serial run
         static label nProcs(const label communicator = 0)
         {
             return procIDs_[communicator].size();
@@ -471,6 +471,13 @@ public:
             return nProcs(communicator) - 1;
         }
 
+        //- Range of process indices for all processes
+        static IntRange<int> allProcs(const label communicator = 0)
+        {
+            // Proc 0 -> nProcs
+            return IntRange<int>(static_cast<int>(nProcs(communicator)));
+        }
+
         //- Communication schedule for linear all-to-master (proc 0)
         static const List<commsStruct>& linearCommunication
         (
diff --git a/src/OpenFOAM/global/fileOperations/masterUncollatedFileOperation/masterUncollatedFileOperation.C b/src/OpenFOAM/global/fileOperations/masterUncollatedFileOperation/masterUncollatedFileOperation.C
index 15be6750a4..e1b9401108 100644
--- a/src/OpenFOAM/global/fileOperations/masterUncollatedFileOperation/masterUncollatedFileOperation.C
+++ b/src/OpenFOAM/global/fileOperations/masterUncollatedFileOperation/masterUncollatedFileOperation.C
@@ -598,12 +598,7 @@ Foam::fileOperations::masterUncollatedFileOperation::read
                 }
 
                 DynamicList<label> validProcs(Pstream::nProcs(comm));
-                for
-                (
-                    label proci = 0;
-                    proci < Pstream::nProcs(comm);
-                    proci++
-                )
+                for (const int proci : Pstream::allProcs(comm))
                 {
                     if (procValid[proci])
                     {
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.C b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.C
index d42491eddf..93a33346e5 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.C
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2018-2019 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -119,7 +119,7 @@ void Foam::globalIndex::reset
 
     label offset = 0;
     offsets_[0] = 0;
-    for (label proci = 0; proci < Pstream::nProcs(comm); ++proci)
+    for (const int proci : Pstream::allProcs(comm))
     {
         const label oldOffset = offset;
         offset += localSizes[proci];
diff --git a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBase.C b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBase.C
index 1f9cb43585..5b90f95a53 100644
--- a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBase.C
+++ b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBase.C
@@ -898,7 +898,7 @@ void Foam::mapDistributeBase::compact(const boolList& elemIsUsed, const int tag)
 
         List<boolList> recvFields(Pstream::nProcs());
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap_[domain];
 
@@ -919,7 +919,7 @@ void Foam::mapDistributeBase::compact(const boolList& elemIsUsed, const int tag)
 
         List<boolList> sendFields(Pstream::nProcs());
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = constructMap_[domain];
 
@@ -976,7 +976,7 @@ void Foam::mapDistributeBase::compact(const boolList& elemIsUsed, const int tag)
 
 
         // Compact out all submap entries that are referring to unused elements
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap_[domain];
 
@@ -1005,7 +1005,7 @@ void Foam::mapDistributeBase::compact(const boolList& elemIsUsed, const int tag)
 
     label maxConstructIndex = -1;
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& map = constructMap_[domain];
 
@@ -1065,7 +1065,7 @@ void Foam::mapDistributeBase::compact
 
         List<boolList> recvFields(Pstream::nProcs());
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap_[domain];
 
@@ -1086,7 +1086,7 @@ void Foam::mapDistributeBase::compact
 
         List<boolList> sendFields(Pstream::nProcs());
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = constructMap_[domain];
 
@@ -1148,7 +1148,7 @@ void Foam::mapDistributeBase::compact
 
             boolList sendElemIsUsed(localSize, false);
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = subMap_[domain];
                 forAll(map, i)
@@ -1177,7 +1177,7 @@ void Foam::mapDistributeBase::compact
 
 
         // Compact out all submap entries that are referring to unused elements
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap_[domain];
 
@@ -1227,7 +1227,7 @@ void Foam::mapDistributeBase::compact
         }
     }
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& map = constructMap_[domain];
 
diff --git a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C
index be48461a9f..e9f9ebccd5 100644
--- a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C
+++ b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2015-2017 OpenFOAM Foundation
-    Copyright (C) 2015-2016, 2019 OpenCFD Ltd.
+    Copyright (C) 2015-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -168,7 +168,7 @@ void Foam::mapDistributeBase::distribute
         // received data.
 
         // Send sub field to neighbour
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap[domain];
 
@@ -216,7 +216,7 @@ void Foam::mapDistributeBase::distribute
         );
 
         // Receive sub field from neighbour
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = constructMap[domain];
 
@@ -398,7 +398,7 @@ void Foam::mapDistributeBase::distribute
             PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking, tag);
 
             // Stream data into buffer
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = subMap[domain];
 
@@ -461,7 +461,7 @@ void Foam::mapDistributeBase::distribute
             Pstream::waitRequests(nOutstanding);
 
             // Consume
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -490,7 +490,7 @@ void Foam::mapDistributeBase::distribute
 
             List<List<T>> sendFields(Pstream::nProcs());
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = subMap[domain];
 
@@ -524,7 +524,7 @@ void Foam::mapDistributeBase::distribute
 
             List<List<T>> recvFields(Pstream::nProcs());
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -592,7 +592,7 @@ void Foam::mapDistributeBase::distribute
 
             // Collect neighbour fields
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -671,7 +671,7 @@ void Foam::mapDistributeBase::distribute
         // received data.
 
         // Send sub field to neighbour
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = subMap[domain];
 
@@ -711,7 +711,7 @@ void Foam::mapDistributeBase::distribute
         flipAndCombine(map, constructHasFlip, subField, cop, negOp, field);
 
         // Receive sub field from neighbour
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             const labelList& map = constructMap[domain];
 
@@ -896,7 +896,7 @@ void Foam::mapDistributeBase::distribute
             PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking, tag);
 
             // Stream data into buffer
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = subMap[domain];
 
@@ -962,7 +962,7 @@ void Foam::mapDistributeBase::distribute
             Pstream::waitRequests(nOutstanding);
 
             // Consume
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -991,7 +991,7 @@ void Foam::mapDistributeBase::distribute
 
             List<List<T>> sendFields(Pstream::nProcs());
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = subMap[domain];
 
@@ -1025,7 +1025,7 @@ void Foam::mapDistributeBase::distribute
 
             List<List<T>> recvFields(Pstream::nProcs());
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -1092,7 +1092,7 @@ void Foam::mapDistributeBase::distribute
 
             // Collect neighbour fields
 
-            for (label domain = 0; domain < Pstream::nProcs(); domain++)
+            for (const int domain : Pstream::allProcs())
             {
                 const labelList& map = constructMap[domain];
 
@@ -1129,7 +1129,7 @@ void Foam::mapDistributeBase::send(PstreamBuffers& pBufs, const List<T>& field)
 const
 {
     // Stream data into buffer
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& map = subMap_[domain];
 
@@ -1165,7 +1165,7 @@ const
     // Consume
     field.setSize(constructSize_);
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& map = constructMap_[domain];
 
diff --git a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
index 73c38e38e1..032041ad9c 100644
--- a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
+++ b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
@@ -1303,7 +1303,7 @@ void Foam::refinementHistory::distribute(const mapDistributePolyMesh& map)
 
     // Create subsetted refinement tree consisting of all parents that
     // move in their whole to other processor.
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         //Pout<< "-- Subetting for processor " << proci << endl;
 
@@ -1412,7 +1412,7 @@ void Foam::refinementHistory::distribute(const mapDistributePolyMesh& map)
     visibleCells_.setSize(mesh.nCells());
     visibleCells_ = -1;
 
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (const int proci : Pstream::allProcs())
     {
         IPstream fromNbr(Pstream::commsTypes::blocking, proci);
         List<splitCell8> newSplitCells(fromNbr);
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/turbulentDFSEMInletFvPatchVectorField.C b/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/turbulentDFSEMInletFvPatchVectorField.C
index 238b84c502..4a5a681a7d 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/turbulentDFSEMInletFvPatchVectorField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/turbulentDFSEMInletFvPatchVectorField.C
@@ -692,7 +692,7 @@ void Foam::turbulentDFSEMInletFvPatchVectorField::calcOverlappingProcEddies
 
     PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& sendElems = map.subMap()[domain];
 
@@ -710,7 +710,7 @@ void Foam::turbulentDFSEMInletFvPatchVectorField::calcOverlappingProcEddies
     pBufs.finishedSends();
 
     // Consume
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& recvElems = map.constructMap()[domain];
 
diff --git a/src/finiteVolume/fvMesh/zoneDistribute/zoneDistribute.C b/src/finiteVolume/fvMesh/zoneDistribute/zoneDistribute.C
index 3194c5ae6d..3cafff4ff9 100644
--- a/src/finiteVolume/fvMesh/zoneDistribute/zoneDistribute.C
+++ b/src/finiteVolume/fvMesh/zoneDistribute/zoneDistribute.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2020 DLR
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -162,7 +163,7 @@ void Foam::zoneDistribute::setUpCommforZone
         PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
         // Stream data into buffer
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             if (domain != Pstream::myProcNo())
             {
@@ -176,7 +177,7 @@ void Foam::zoneDistribute::setUpCommforZone
         // wait until everything is written.
         pBufs.finishedSends();
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             send_[domain].clear();
 
diff --git a/src/finiteVolume/fvMesh/zoneDistribute/zoneDistributeI.H b/src/finiteVolume/fvMesh/zoneDistribute/zoneDistributeI.H
index 2289be2509..2c733ec6bb 100644
--- a/src/finiteVolume/fvMesh/zoneDistribute/zoneDistributeI.H
+++ b/src/finiteVolume/fvMesh/zoneDistribute/zoneDistributeI.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2019-2020 DLR
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -184,7 +185,7 @@ Foam::Map<Type> Foam::zoneDistribute::getDatafromOtherProc
         PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
         // Stream data into buffer
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             if (domain != Pstream::myProcNo())
             {
@@ -200,7 +201,7 @@ Foam::Map<Type> Foam::zoneDistribute::getDatafromOtherProc
 
         Map<Type> tmpValue;
 
-        for (label domain = 0; domain < Pstream::nProcs(); domain++)
+        for (const int domain : Pstream::allProcs())
         {
             if (domain != Pstream::myProcNo())
             {
diff --git a/src/functionObjects/field/STDMD/STDMD.C b/src/functionObjects/field/STDMD/STDMD.C
index 65d47e6887..4fc192d670 100644
--- a/src/functionObjects/field/STDMD/STDMD.C
+++ b/src/functionObjects/field/STDMD/STDMD.C
@@ -293,9 +293,9 @@ void Foam::functionObjects::STDMD::calcAp()
             Log<< tab << "# " << name()
                 << ": Populating the global Rx #" << endl;
             label m = 0;
-            for (label i = 0; i < Pstream::nProcs(); ++i)
+            for (const int i : Pstream::allProcs())
             {
-                label mRows = RxList[i].m();
+                const label mRows = RxList[i].m();
 
                 Rx.subMatrix(m, 0, mRows) = RxList[i];
 
diff --git a/src/functionObjects/field/externalCoupled/externalCoupled.C b/src/functionObjects/field/externalCoupled/externalCoupled.C
index e30488bbea..927e764d27 100644
--- a/src/functionObjects/field/externalCoupled/externalCoupled.C
+++ b/src/functionObjects/field/externalCoupled/externalCoupled.C
@@ -117,7 +117,7 @@ void Foam::functionObjects::externalCoupled::readColumns
 
         // Read data from file and send to destination processor
 
-        for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             // Temporary storage
             List<scalarField> values(nColumns);
@@ -188,7 +188,7 @@ void Foam::functionObjects::externalCoupled::readLines
 
         // Read line from file and send to destination processor
 
-        for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             // Number of rows to read for processor proci
             const label procNRows = globalFaces.localSize(proci);
@@ -314,7 +314,7 @@ void Foam::functionObjects::externalCoupled::writeGeometry
                 allPoints.clear();
                 allFaces.clear();
 
-                for (label proci=0; proci < Pstream::nProcs(); ++proci)
+                for (const int proci : Pstream::allProcs())
                 {
                     allPoints.append(collectedPoints[proci]);
                     allFaces.append(collectedFaces[proci]);
diff --git a/src/functionObjects/randomProcesses/energySpectrum/energySpectrum.C b/src/functionObjects/randomProcesses/energySpectrum/energySpectrum.C
index 85032821ec..fb8f794b98 100644
--- a/src/functionObjects/randomProcesses/energySpectrum/energySpectrum.C
+++ b/src/functionObjects/randomProcesses/energySpectrum/energySpectrum.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -235,7 +235,7 @@ bool Foam::functionObjects::energySpectrum::write()
             vectorField Uijk(nGlobalCells);
             vectorField Cijk(nGlobalCells);
 
-            for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+            for (const int proci : Pstream::allProcs())
             {
                 UIPstream fromProc(proci, pBufs);
                 vectorField Up;
diff --git a/src/lagrangian/basic/InteractionLists/InteractionLists.C b/src/lagrangian/basic/InteractionLists/InteractionLists.C
index ffd9f041bc..4e1535ed09 100644
--- a/src/lagrangian/basic/InteractionLists/InteractionLists.C
+++ b/src/lagrangian/basic/InteractionLists/InteractionLists.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -1172,7 +1172,7 @@ void Foam::InteractionLists<ParticleType>::sendReferredData
 
     prepareParticlesToRefer(cellOccupancy);
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& subMap = cellMap().subMap()[domain];
 
@@ -1211,7 +1211,7 @@ void Foam::InteractionLists<ParticleType>::receiveReferredData
 
     referredParticles_.setSize(cellMap().constructSize());
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& constructMap = cellMap().constructMap()[domain];
 
diff --git a/src/lagrangian/spray/clouds/Templates/SprayCloud/SprayCloudI.H b/src/lagrangian/spray/clouds/Templates/SprayCloud/SprayCloudI.H
index a5fdbf9d8f..3edd6376c9 100644
--- a/src/lagrangian/spray/clouds/Templates/SprayCloud/SprayCloudI.H
+++ b/src/lagrangian/spray/clouds/Templates/SprayCloud/SprayCloudI.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -133,7 +133,7 @@ inline Foam::scalar Foam::SprayCloud<CloudType>::penetration
         // flatten the mass lists
         List<scalar> allMass(nParcelSum, Zero);
         SortableList<scalar> allDist(nParcelSum, Zero);
-        for (label proci = 0; proci < Pstream::nProcs(); proci++)
+        for (const int proci : Pstream::allProcs())
         {
             SubList<scalar>
             (
diff --git a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementRefine.C b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementRefine.C
index 330cc3426e..f5d9c5f395 100644
--- a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementRefine.C
+++ b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementRefine.C
@@ -2494,7 +2494,7 @@ Foam::meshRefinement::balanceAndRefine
     //    globalIndex globalCells(mesh_.nCells());
     //
     //    Info<< "** Distribution before balancing/refining:" << endl;
-    //    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    //    for (const int procI : Pstream::allProcs())
     //    {
     //        Info<< "    " << procI << '\t'
     //            << globalCells.localSize(procI) << endl;
@@ -2505,7 +2505,7 @@ Foam::meshRefinement::balanceAndRefine
     //    globalIndex globalCells(cellsToRefine.size());
     //
     //    Info<< "** Cells to be refined:" << endl;
-    //    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    //    for (const int procI : Pstream::allProcs())
     //    {
     //        Info<< "    " << procI << '\t'
     //            << globalCells.localSize(procI) << endl;
@@ -2567,7 +2567,7 @@ Foam::meshRefinement::balanceAndRefine
         //    globalIndex globalCells(mesh_.nCells());
         //
         //    Info<< "** Distribution after balancing:" << endl;
-        //    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+        //    for (const int procI : Pstream::allProcs())
         //    {
         //        Info<< "    " << procI << '\t'
         //            << globalCells.localSize(procI) << endl;
@@ -2625,7 +2625,7 @@ Foam::meshRefinement::balanceAndRefine
     //    globalIndex globalCells(mesh_.nCells());
     //
     //    Info<< "** After refinement distribution:" << endl;
-    //    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    //    for (const int procI : Pstream::allProcs())
     //    {
     //        Info<< "    " << procI << '\t'
     //            << globalCells.localSize(procI) << endl;
diff --git a/src/meshTools/AMIInterpolation/AMIInterpolation/advancingFrontAMI/advancingFrontAMIParallelOps.C b/src/meshTools/AMIInterpolation/AMIInterpolation/advancingFrontAMI/advancingFrontAMIParallelOps.C
index e67d9e6e40..4a87d1c050 100644
--- a/src/meshTools/AMIInterpolation/AMIInterpolation/advancingFrontAMI/advancingFrontAMIParallelOps.C
+++ b/src/meshTools/AMIInterpolation/AMIInterpolation/advancingFrontAMI/advancingFrontAMIParallelOps.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -76,7 +76,7 @@ void Foam::advancingFrontAMI::distributePatches
 {
     PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
-    for (label domain = 0; domain < Pstream::nProcs(); ++domain)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& sendElems = map.subMap()[domain];
 
@@ -132,7 +132,7 @@ void Foam::advancingFrontAMI::distributePatches
     }
 
     // Consume
-    for (label domain = 0; domain < Pstream::nProcs(); ++domain)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& recvElems = map.constructMap()[domain];
 
diff --git a/src/meshTools/output/foamVtkInternalMeshWriter.C b/src/meshTools/output/foamVtkInternalMeshWriter.C
index a910aea8a7..d48b583016 100644
--- a/src/meshTools/output/foamVtkInternalMeshWriter.C
+++ b/src/meshTools/output/foamVtkInternalMeshWriter.C
@@ -712,7 +712,7 @@ bool Foam::vtk::internalMeshWriter::writeProcIDs()
         }
 
         // Per-processor ids
-        for (label proci=0; proci < Pstream::nProcs(); ++proci)
+        for (const int proci : Pstream::allProcs())
         {
             vtk::write(format(), proci, procMaps.localSize(proci));
         }
diff --git a/src/meshTools/output/foamVtkPatchMeshWriter.C b/src/meshTools/output/foamVtkPatchMeshWriter.C
index f9536d548d..6896777f7f 100644
--- a/src/meshTools/output/foamVtkPatchMeshWriter.C
+++ b/src/meshTools/output/foamVtkPatchMeshWriter.C
@@ -697,7 +697,7 @@ bool Foam::vtk::patchMeshWriter::writeProcIDs()
         if (Pstream::master())
         {
             // Per-processor ids
-            for (label proci=0; proci < Pstream::nProcs(); ++proci)
+            for (const int proci : Pstream::allProcs())
             {
                 vtk::write(format(), proci, procSizes.localSize(proci));
             }
diff --git a/src/meshTools/processorLOD/box/box.C b/src/meshTools/processorLOD/box/box.C
index d7ebd5cc66..4bf8dffc5f 100644
--- a/src/meshTools/processorLOD/box/box.C
+++ b/src/meshTools/processorLOD/box/box.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017 OpenCFD Ltd.
+    Copyright (C) 2017-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -61,7 +61,7 @@ void Foam::processorLODs::box::writeBoxes
     );
 
     label verti = 0;
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         if (proci == Pstream::myProcNo())
         {
@@ -111,7 +111,7 @@ void Foam::processorLODs::box::setRefineFlags
     PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
     // Identify src boxes that can be refined and send to all remote procs
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         if (proci != Pstream::myProcNo())
         {
@@ -124,7 +124,7 @@ void Foam::processorLODs::box::setRefineFlags
 
     // Test each remote src bb with local tgt objects to identify which remote
     // src boxes can/should be refined
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         if (proci == Pstream::myProcNo())
         {
@@ -345,7 +345,7 @@ bool Foam::processorLODs::box::doRefineBoxes
     List<DynamicList<label>> newToOld(Pstream::nProcs());
 
 
-    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
+    for (const int proci : Pstream::allProcs())
     {
         if (proci == Pstream::myProcNo())
         {
diff --git a/src/overset/cellCellStencil/inverseDistance/inverseDistanceCellCellStencil.C b/src/overset/cellCellStencil/inverseDistance/inverseDistanceCellCellStencil.C
index 616ecce320..3f40b84503 100644
--- a/src/overset/cellCellStencil/inverseDistance/inverseDistanceCellCellStencil.C
+++ b/src/overset/cellCellStencil/inverseDistance/inverseDistanceCellCellStencil.C
@@ -368,7 +368,7 @@ void Foam::cellCellStencils::inverseDistance::markPatchesAsHoles
 
     // 2. Send over srcMesh bits that overlap tgt and do calculation
     pBufs.clear();
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
@@ -385,7 +385,7 @@ void Foam::cellCellStencils::inverseDistance::markPatchesAsHoles
         }
     }
     pBufs.finishedSends();
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
@@ -537,7 +537,7 @@ void Foam::cellCellStencils::inverseDistance::markDonors
     DynamicList<label> tgtOverlapProcs(Pstream::nProcs());
     // (remote) processors where the src overlaps my tgt
     DynamicList<label> srcOverlapProcs(Pstream::nProcs());
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
diff --git a/src/overset/cellCellStencil/trackingInverseDistance/trackingInverseDistanceCellCellStencil.C b/src/overset/cellCellStencil/trackingInverseDistance/trackingInverseDistanceCellCellStencil.C
index 7f643ba29e..b19b1b544f 100644
--- a/src/overset/cellCellStencil/trackingInverseDistance/trackingInverseDistanceCellCellStencil.C
+++ b/src/overset/cellCellStencil/trackingInverseDistance/trackingInverseDistanceCellCellStencil.C
@@ -250,7 +250,7 @@ void Foam::cellCellStencils::trackingInverseDistance::markPatchesAsHoles
 
     // 2. Send over srcMesh bits that overlap tgt and do calculation
     pBufs.clear();
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
@@ -267,7 +267,7 @@ void Foam::cellCellStencils::trackingInverseDistance::markPatchesAsHoles
         }
     }
     pBufs.finishedSends();
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
@@ -373,7 +373,7 @@ void Foam::cellCellStencils::trackingInverseDistance::markDonors
     DynamicList<label> tgtOverlapProcs(Pstream::nProcs());
     // (remote) processors where the src overlaps my tgt
     DynamicList<label> srcOverlapProcs(Pstream::nProcs());
-    for (label procI = 0; procI < Pstream::nProcs(); procI++)
+    for (const int procI : Pstream::allProcs())
     {
         if (procI != Pstream::myProcNo())
         {
diff --git a/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C b/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
index d51804c3b9..c4810938ca 100644
--- a/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
+++ b/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
@@ -109,7 +109,7 @@ void Foam::ptscotchDecomp::check(const int retVal, const char* str)
 //    globalIndex globalCells(initxadj.size()-1);
 //
 //    bool hasZeroDomain = false;
-//    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+//    for (const int proci : Pstream::allProcs())
 //    {
 //        if (globalCells.localSize(proci) == 0)
 //        {
diff --git a/src/randomProcesses/noise/noiseModels/surfaceNoise/surfaceNoise.C b/src/randomProcesses/noise/noiseModels/surfaceNoise/surfaceNoise.C
index 66d7b22cf2..c01eaafb0d 100644
--- a/src/randomProcesses/noise/noiseModels/surfaceNoise/surfaceNoise.C
+++ b/src/randomProcesses/noise/noiseModels/surfaceNoise/surfaceNoise.C
@@ -169,7 +169,7 @@ void surfaceNoise::readSurfaceData
                 p *= rhoRef_;
 
                 // Send subset of faces to each processor
-                for (label procI = 0; procI < Pstream::nProcs(); ++procI)
+                for (const int procI : Pstream::allProcs())
                 {
                     label face0 = procFaceOffset[procI];
                     label nLocalFace =
diff --git a/src/sampling/meshToMesh/meshToMeshParallelOps.C b/src/sampling/meshToMesh/meshToMeshParallelOps.C
index 5b3faec2ca..0f2a393c50 100644
--- a/src/sampling/meshToMesh/meshToMeshParallelOps.C
+++ b/src/sampling/meshToMesh/meshToMeshParallelOps.C
@@ -322,7 +322,7 @@ void Foam::meshToMesh::distributeCells
     procLocalFaceIDs.setSize(Pstream::nProcs());;
 
 
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& sendElems = map.subMap()[domain];
 
@@ -501,7 +501,7 @@ void Foam::meshToMesh::distributeCells
     pBufs.finishedSends();
 
     // Consume
-    for (label domain = 0; domain < Pstream::nProcs(); domain++)
+    for (const int domain : Pstream::allProcs())
     {
         const labelList& recvElems = map.constructMap()[domain];
 
diff --git a/src/thermophysicalModels/radiation/radiationModels/viewFactor/viewFactor.C b/src/thermophysicalModels/radiation/radiationModels/viewFactor/viewFactor.C
index f48f1081bf..2288d8457a 100644
--- a/src/thermophysicalModels/radiation/radiationModels/viewFactor/viewFactor.C
+++ b/src/thermophysicalModels/radiation/radiationModels/viewFactor/viewFactor.C
@@ -139,7 +139,7 @@ void Foam::radiation::viewFactor::initialise()
         DebugInFunction
             << "Insert elements in the matrix..." << endl;
 
-        for (label procI = 0; procI < Pstream::nProcs(); procI++)
+        for (const int procI : Pstream::allProcs())
         {
             insertMatrixElements
             (